In contrast to back-mounted systems in which one or two dive cylinders are affixed to a diver's Buoyancy Control Device (BCD) in such manner that the cylinder(s) are located on the diver's back, side-mount configurations position a cylinder along each side of a diver's torso, with the cylinder valves located comfortably near the diver's arm-pits. The side-mount arrangement was first developed in the 1960s by British cave explorers, looking for a method to more effectively carry dive cylinders alongside the outer thigh. This allowed them to crawl, or wiggle, through dry cave sections, whilst presenting a secure method of attachment for passing through submerged areas. American cave divers incorporated the ‘English system’ in the 1970s to facilitate exploration of Florida's vast network of submerged caves. However, the ensuing long swims placed greater emphasis on buoyancy and trim and the need to reposition the cylinder from low against the thigh, up to the armpit and against the torso. The rigs used by these underwater cave explorers were either built ‘from scratch’ or incorporated harness and bladder adaptations from ‘off-the-shelf’ scuba equipment. The first commercial side-mount diving system was designed by Lamar Hires in the mid 1990s and manufactured by Dive Rite. In 2001 Brett Hemphill designed the Armadillo Side-Mount Harness that incorporated a number of innovative features. Widespread popularity of side-mount systems did not truly emerge until the mid 2010s with growing interest in technical and cave diving. Commercial production of various side-mount designs by the likes of DiveRite, Halcyon, Hollis, OMD, SCUBAPRO, UTD and others have given rise to BCDs such as the Razor 2.0, Deep Stealth, UTD-Z Trim, Aquamundo, Diamond, Armadillo, Nomad, Contour, SMS75, SMS100 and Katana. (Reference Source: Wikipedia—Sidemount Diving)
Recreational side-mount BCDs, i.e., BCDs designed for divers that perform neither decompression dives nor cave dives were also popularized in the mid 2010s by firms such as Hollis.
Prior art to affix a scuba cylinder's lower point of attachment to a side-mount BCD universally includes three parts: 1) a bolt snap, 2) a piece of stout braided cord strong enough to support the weight of a dive cylinder, made into a loop by tying the two ends with an overhand knot (or a piece of shock cord similarly configured—provided the upper point of attachment is capable of supporting the cylinder's weight), and 3) either a web cylinder band having an appropriate clamping device or a hose-clamp that encircles a dive cylinder and is tightened thereto. The three are attached to each other by first passing the loop through the bolt snap's ring and then around the entire bolt snap, or by passing the cord through the bolt snap's ring before tying the ends. With a tri-glide loosely in place on a web cylinder band, the knot forming the loop of cord is passed through the loop of web formed at the tri-glide and held fast by tightening the loop of web, thereby trapping the knot so that the cord cannot pull free of the tri-glide. The web cylinder band is then suitably positioned on the dive cylinder and tightened thereto. Alternatively, the knot forming the loop of cord is tucked under a hose clamp immediately prior to tightening the hose-clamp around a dive cylinder.
With the bolt snap thus secured to the side of a dive cylinder at an appropriate location, the lower portion of the cylinder may now be attached to the metal rail affixed to either side of the lower rear portion of BCD backplates designed for side-mount configurations, or to a D ring located low on the BCD, for instance on the web waistband of BCDs so equipped. Prior to entering the water, this arrangement must support the weight of a dive cylinder.
A number of arrangements have been developed over the years to position the upper portion of a dive cylinder so that the cylinder valve comfortably sits near the diver's armpit. One such arrangement includes a shock cord formed into a loop, both ends of which are attached to the upper back portion of BCDs designed for side-mount. The shock cord may also pass through a loop secured to the shoulder harness in order to position the shock cord for ready access by the diver. When stretched, the loop of shock cord is then passed around the cylinder valve and hooked around either the valve handle or the post opposite. Another arrangement has one end of a length of shock cord tied or clipped by means of a bolt snap to the upper back portion of BCDs designed for side-mount. A bolt snap is affixed to the free end which, when stretched, is made to pass around the cylinder valve before being clipped onto a D ring affixed to the BCD shoulder harness. A variation of this includes a metal ring affixed to the free end followed by a chain link and bolt snap. The bolt snap is then clipped to a D ring on the BCD shoulder harness. A bolt snap with the snap portion tightly secured to the neck of a dive cylinder is then clipped to the metal ring. This arrangement provides support to the cylinder whether or not the lower point of attachment is secured. In the case of cylinders used to augment BCDs having back mounted cylinders, a short length of cord is passed through the ring of a bolt snap and tied so as to form a loop just large enough to pass over the cylinder valve prior to mounting a regulator on the valve. The bolt snap is then clipped to a D ring mounted on the shoulder harness. This latter arrangement often uses shock cord for the lower point of attachment and relies on the upper bolt snap/cord to support the cylinder's weight.
The manner in which a dive cylinder is thus affixed to a BCD in a position to one side or the other of a diver's torso may be accomplished before or after entering the water. When in the water, unclipping the lower portion of the dive cylinder allows it to be maneuvered in an arc so as to position the cylinder above the diver's head, in line with the diver's body by leaving the upper attachment in place. Once accomplished with one or both side mounted cylinders, the diver is thus able to swim through confined areas such as those encountered in caves or wrecks. Having exited such confined spaces, the diver then repositions the cylinder(s) back along the torso and re-clips the bolt snap to the lower point of attachment.
The length of cord between the bolt snap and dive cylinder at the lower point of attachment is determined to some extent by the need to reach between the diver's torso and the cylinder in order to clip the bolt snap onto or unclip the bolt snap from the BCD. This is exacerbated when, in the case of cold water, the diver must wear gloves for thermal protection. In such cases, bolt snaps are usually larger to facilitate easier manipulation. Bulky gloves necessitate establishing a greater distance between the dive cylinder and BCD in order to facilitate reaching between the two during clipping and unclipping activities. In any event, the distance established by the combination of bolt snap and cord creates the opportunity for the dive cylinder to move freely within an arc, more so for cold water divers.
This arc of movement becomes critical whenever utilizing aluminum dive cylinders which change from negative buoyancy when full to positive buoyancy over the course of a dive as the breathing gas is consumed. Unfortunately, aluminum cylinders are almost exclusively utilized by cave divers and rental facilities at dive destinations. When utilizing such cylinders, the cylinder begins by being appropriately positioned along the diver's torso when swimming in a normal, belly down orientation, but then rides with the lower portion of the cylinder floating ever higher and away from the torso over the course of a dive. The angle thus formed by the cylinder and diver's torso can easily exceed 45 degrees. This then diminishes the streamlined benefit of having cylinders tucked along the diver's torso in order to minimize breathing effort and gas consumption. The added cross-sectional dimension of diver/cylinder combination arising from poorly positioned cylinders also increases the need to re-configure cylinders for confined water operation when passing through reasonably open swim-throughs or doorways in wrecks even though properly positioned cylinders would obviate the need to re-configure.
To overcome the previously identified weakness, divers utilizing aluminum cylinders typically add one or two pair of D rings to their BCD waistband to enable repositioning the lower point of attachment closer to the belt buckle, that is, closer to the midline, so as to reduce the degree to which the lower portion of the cylinder rides upwards. Alternatively, some diver's utilize sliding D rings that can be repositioned during the dive to create the same effect. However, these arrangements exacerbate the availability of valuable real estate along the waistband's length otherwise needed for weight systems and accessories such as dive knives and cutting tools. Furthermore, the cylinders still float away from the diver's torso when swimming in anything other than a belly down orientation.
This situation is minimized when utilizing steel cylinders which remain negatively buoyant regardless of their state of fill. Even so, gravity creates the same effect of poorly positioned cylinders when swimming in anything other than a belly-down orientation, regardless of the BCD point of attachment. Moreover, the change in centre of gravity occurring when heavy steel cylinders are positioned for swim-throughs makes aluminum cylinders the preferred choice for cave divers.
Finally, the issue of movement of a dive cylinder, even to a small degree creates issues when walking on a moving vessel or negotiating a rocky shoreline. Loss of balance becomes dangerous when two cylinders, especially heavier steel cylinders, are attached to the BCD prior to entering the water.
It is apparent from the foregoing that the prior art fails to hold the lower portion of a dive cylinder in its desired position, that is, close to the diver's torso, regardless of the cylinder's state of fill and regardless of the diver's orientation within the water, while aboard dive vessels, or while walking on rocky shorelines. Moreover, the need to reach between the diver's torso and a dive cylinder in order to manipulate a bolt snap when clipping to or unclipping from a BCD, especially whilst wearing thick neoprene gloves, is problematic.